The present invention generally relates to a torque transmitting coupling, particularly to a torque transmitting coupling for coupling a spring clutch connected a driving system, and a driven system. The present invention also relates to an image forming apparatus, particularly to an image forming apparatus provided with an image transfer device the positioning of which is controlled by the aforementioned torque transmitting coupling.
The photoconductor drum and image transfer device in the example of a copying machine can be withdrawn from the machine body for maintenance, removing a jammed sheet, etc. Accordingly, the main driven axle of the associated position regulating mechanisms constituting a driven system is coupled with a driving system through a torque transmitting coupling, which typically consists of interlocking couplers, fixed to the drive and driven systems respectively.
A spring clutch is employed in the copying machine for transmitting driving system torque to the main driven axle. The spring clutch inter alia consists of a spring acting on a clutch boss, and it is often disposed between the coupling and the driving system. When driving system torque is applied in the winding direction of the spring, the diameter of the spring contracts, engaging the clutch. Driving system torque applied in the opposite direction unwinds the spring, expanding it diametrically and disengaging the clutch.
If the driven system main axle is turned independently, it can happen that the spring clutch becomes engaged through the torque transmitting coupling, since the spring clutch is engaged and disengaged mechanically. Particularly in the case of the copying machine, while mounting or dismounting the image transfer device and associated elements, external torque is transmitted from the driven system to the driving system, such that the spring clutch becomes engaged, rotating the driving system, hindering the mounting/dismounting operations.